Iron has been administered mixed with food to workers building a bridge near Rio. In the first group (88 individuals) ferrous sulfate 0.5 gr per day, has been given mixed with mandioca flour, for a 30 days period. In the second group (35 individuals) after a similar period, iron was given for another month in the form of ferric ammonium citrate, brown, 0.7 gr per day dissolved bean soup. The results could be seen in the table below: It has been shown a marked improvement in individuals with hemoglobin content below 10.00 gr per 100 cu. blood. Individuals with hemoglobin slightly below normal are not improved by this treatment. In the dosage above given any health disturbance has been observed in the 123 individuals during, this two months period with iron administration.